I am interested in an LED driver IC. It drives a 40W E27 LED with a 12V fan.

The logo looks kind of like "JD." The IC number is difficult to read: something "960?S" (see picture.)

It seems to drive a buck converter with two outputs: 12V (for the fan) and about 90-100V for the LEDs. It uses a transformer / inductor combination in the path of the driver.

So there is one driver IC and one "transformer" (this is not an insulated driver!) driving two voltages.

enter image description here


2 Answers 2


Most likely it's a Chinese-made primary-side regulated (PSR) constant-current flyback converter chip with internal MOSFET. It won't be easy to find the brand/model or even a datasheet, but there are numerous chips of this type in the market.

There's a 2R2 1% resistor. Probably it sets the output (LED) current.

M7 diodes (D1..D4) are kinda SMD equivalent of 1N4007. There are 4 of them. At first, I thought that they form a bridge rectifier because there are two white cables coming to that side (probably AC voltage input) and a big electrolytic capacitor (could be a few micro Farads, 400/450V). But the PCB tracks don't look like so.

D5 (couldn't read its model) could be either a part of the snubber block or rectifier diode coming from the aux winding for chip supply I don't see a small capacitor for this purpose, though. So I'm not sure what D5 does.

The 39k resistor to the ground probably determines the open (unloaded or maximum) output voltage, since (as you said) it's an LED driver. One of the main problems of constant-current LED drivers is LED disconnection which leads the output voltage to rise until the circuit breaks down. So the converter should sense and thus limit the output voltage. This helps to limit the output power as well since the internal MOSFET can easily thermally run away.

The secondary side is blocked by your thumb. So I can't make a guess. But I see an electrolytic capacitor, and probably there's a rectifier diode plus a bleeder resistor.




  1. I asked PhotoShop for help, but no luck.

  2. The logo looks like "D".

  3. The Q&As in Ref 1, Ref 2 below and the schematic might help a bit.


  1. Another typical transformerless AC to DC LED driver schematic


  1. Constant Current Light Transformer AC200-240V Power Adapter For LED Bulb DIY - AliExpress]6

transformer led driver


(1) What's the voltage used to power LEDs inside an LED light bulb? Asked 3 months ago Active 3 months ago Viewed 179 times

(2) Is this power supply suitable for powering these chip on board (COB) LEDs? Asked 13 days ago Active 11 days ago Viewed 351 times

(3) How can Rpi Python PWM GPIO pins control and dim LED strips of 1W 350mA? - EESE 2021mar13

(4) Transformerless AC/DC Constant Current Driver MBI6001 - ÓMacroblock 2003jan

(5) Constant Current Light Transformer AC200-240V Power Adapter For LED Bulb DIY - AliExpress

(6) LED Lamp Driver 1-36W 110-265VAC built-in constant current source output 300mA - AliExpress US$0.5 ~ US$4

(7) Controlling LED lighting systems: introducing the LED driver - LedMagazine 2004dec10

(8) Crushing and hacking LED lamps - Big Clive

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    \$\begingroup\$ This actually is not an answer. \$\endgroup\$ Apr 26, 2021 at 5:10
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    \$\begingroup\$ @Chupacabras there is no way to include an inline image in a comment \$\endgroup\$
    – jsotola
    Apr 26, 2021 at 6:10
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    \$\begingroup\$ Thanks for all your answers! But the key problem is this buck converter is doing two output voltages (12V = fan; 100V = LED). Thus - sorry- your schematics dont match. \$\endgroup\$ Apr 26, 2021 at 11:20
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    \$\begingroup\$ @jsotola - Hi, On its own, including an inline image is not a justification for something to be an answer. However, this is an answer attempt i.e. there could have been something useful to the OP here (although the OP's recent comment suggests that is not the case). As always, it is up to the community to use voting to show their view of whether an answer is useful or not. Also see discussion on Meta about similar answers here. Thanks. \$\endgroup\$
    – SamGibson
    Apr 26, 2021 at 12:17
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    \$\begingroup\$ Sorry, but did anyone read my addition: It´s not about driving LEDs, its about that this device produces two voltages to a kind of transformer setup... But i gave up. Thanks for trying. \$\endgroup\$ May 8, 2021 at 7:51

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